Every time I start working with a new client I get asked:"which form of cardio is best, low impact or high intensity interval training?"

The reality is that both have many merits, having said that I tend to recommend new clients low impact steady state cardio in 99% of the time IF fat loss is the primary goal. There are many reasons why, which I'll share with you below.

Joint Health

Sprinting is definitely going to put more stress on your joints rather than fast walking. When you're doing frequent cardio sessions this could become an issue, especially when we consider that a lot of people with fat loss goals are naturally going to be carrying extra mass which will compound the overall stress on the joints. For this reasons I prefer low impact cardio, I feel it carries far less risks and allows you to recover much better. 

Stress

High impact interval training is far more stressful than fast walking, which isn't always an issue. However for many people stress is in itself a big problem within their lives, therefore contributing to that on top of your resistance workouts isn't always a good idea. In order to help manage stress and avoid excessive cortisol production, I'd recommend doing low impact cardio in most instances. If your body is over stressed it will potentially become more catabolic. 

Injury Prevention

In terms of muscle recovery specifically, there is no question that low impact cardio is a better option over something like sprinting in my opinion, specially when the runners are lucking muscular strength in their legs.

When you sprint for example your muscle fibres are going to be under a lot of pressure. Baring in mind that you're already putting them under stress when you lift in the gym, you could over do it and make your muscles more vulnerable to tears for instances. At the very least it will effect recovery and potentially lead to a reduction in performance in the gym. 

I feel that low impact cardio is a great option for the majority of people and I actually tend to have my clients do it year round, for the CV health benefits, along with stress management and joint health.